* {
  margin: 0;
  padding: 0;
}

a {
  text-decoration: none;
}

body {
  padding: 20px;
  padding-right: 100px;
}

.box {
  width: 100%;
  height: 10000px;
}

.box > div {
  margin-bottom: 20px;
}

.box .header {
  height: 500px;
  background-color: yellowgreen;
}

.box .item {
  width: 100%;
  height: 200px;
  background-color: red;
}

.nav {
  width: 50px;
  position: fixed;
  top: 50%;
  right: 10px;
}

.nav .navItem {
  display: block;
  width: 50px;
  height: 50px;
  font-size: 12px;
  width: 100%;
  background-color: yellowgreen;
  margin-bottom: 5px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.nav .navItem.active {
  color: red;
}
